Exhaust gas turbochargers are used for example in internal combustion engines in order to increase the pressure level in the fresh gas during the gas exchange process. Such an exhaust gas turbocharger can be equipped with a radial compressor, comprising a compressor wheel, by means of which the respective gas can be delivered and compressed. For this purpose, the compressor wheel can comprise an axial inlet side and a radial outlet side and be arranged in a compressor space. An inlet channel leads to the inlet side of the compressor wheel and in the case of an internal combustion engine to a low-pressure region of a fresh gas system equipped with the exhaust gas turbocharger. An outlet channel leads from the outlet side of the compressor wheel away to the high-pressure side of the fresh gas system.
In order to ensure a smooth and in particular frictionless rotary movement of the compressor wheel during the operation in the exhaust gas turbocharger, an intermediate space in the manner of a gap has to remain between the compressor wheel and a compressor housing forming the compressor space so that compressor wheel and compressor housing are arranged spaced from one another and consequently no interfering friction effects between these components can occur. However, a gap which is designed too large, i.e. a gap width of such a gap that is too large leads to an undesirable weakening of the performance of the exhaust gas turbocharger using the compressor wheel since such a gap leads to a reduction of the rate of delivery of the compressor wheel.
In order to ensure an optimal functionality with a maximum rate of delivery of the exhaust gas turbocharger the gap between compressor wheel and compressor housing that was explained beforehand is required on the one hand, but on the other hand, this gap should have as small as possible a gap width.